Flow Battery Market: Commercial Flow Battery Products

Have you ever wondered if commercial redox flow battery (RFB) energy storage systems (ESSs) exist? Have you ever been curious about the leading RFB manufacturers? Are you interested in learning the latest product designs and key trends in the RFB market? Are you a developer, an investor or a technology enthusiast?

If your answer was ‘Yes‘ to any of the questions, then this article is for you! The article covers:

• Leading RFB ESS products

• Key product technical specifications

• Key competencies

The manufacturers are arranged in ascending alphabetical order. Let’s dive into it!

ESS Inc.

ESS Inc. (“ESS”) is a US-based company headquartered in Portland, Oregon. ESS specializes in the design and manufacturing of all iron flow battery (IFB). ESS’s IFB is a hybrid flow battery since the redox active material in the negative compartment of the cell is deposited as a solid layer on the electrode. ESS is publicly traded on the New York Stock Exchange (NYSE) under sticker symbol GWH. ESS has 2 main commercial products:

• Energy Warehouse, with a 90 kW / 400 kWh direct current (DC) rating, for the commercial and industrial market (C&I)

• Energy Center, with a 145 kW / 1160 kWh DC rating, for the utility-scale market

The key specifications of the Energy Warehouse include:

• Maximum power: 90 kW DC

• Storage duration: 4 hours to 12 hours

• Lifetime: 25 years

• Roundtrip efficiency (RTE): 70% to 75% (DC)

Key competencies

• Domestic (American) supply chain: ESS can maximize the benefits of the Inflation Reduction Act (IRA).

• Intellectual Property (IP): ESS owns the patent for its IFB technology.

Invinity Energy Systems Plc

Invinity Energy Systems Plc (“Invinity“) is an Anglo-American RFB company founded in 2020 from the merger of two RFB companies: UK-based RedT Energy and US-based Avalon Battery. Invinity is involved in the research and development (R&D), manufacturing in addition to engineering, procurement and construction (EPC) of vanadium redox flow battery (VRFB). Invinity is publicly traded on the London Stock Exchange under sticker symbol IES.L. Invinity has manufacturing hubs in London, UK; Vancouver, Canada and Suzhou, China.

Invinity’s latest ESS product is the VS3-022 modular battery unit with a 78 kW / 230 kWh DC rating.

The following are the key performance characteristics of VS3-022:

• Maximum power: 78 kW DC

• Storage duration: 2.25 hours to 8 hours

• Lifetime: > 20,000 cycles (~27 years assuming 2 cycles per day)

• RTE: 75% (DC)

Key competency

• Global manufacturing capability: has operations in North America, Europe and Asia.

Largo Inc.

Largo Inc. (“Largo“) is a vertically integrated company best known for its global vanadium mining operations. Largo Clean Energy is the division of Largo that manufactures vanadium redox flow batteries (VRFBs). Largo is listed in NASDAQ under sticker symbol LGO. VCHARGE, with a 1200 kW / 6000 kWh DC rating, is Largo’s first commercial VRFB product.

The key specifications of VCHARGE are listed below:

• Maximum power: 1200 kW DC

• Storage duration: 5 to 8.3 hours

• Lifetime: 20 years

• RTE: 78% (DC); 68% (AC)

Key competency

• Vertical integration: mitigates the impacts of the frequent fluctuation of vanadium pentoxide prices on the VRFB business.

• IP ownership: Largo owns the patent for its VRFB technology.

Redflow Limited

Redflow Limited (“Redflow“) is an Australian RFB company founded in 2005. Redflow runs R&D, design and manufacturing of zinc-bromine redox flow batteries (ZBRFBs) in-house. Redflow is listed on the Australian Securities Exchange (ASX) under sticker symbol REFXF.

Energy Pod200, 60 kW / 200 kWh rating, is the building block of Redflow’s ZBRFB systems.

The following are the key specifications of Energy Pod200:

• Maximum DC power: 60 kW

• Storage duration: 4 hours to 12 hours

• Lifetime: undisclosed

• RTE: 70% to 80% (DC)

Key competency

• Modularity: the core unit of Energy Pod200 is the 10-kWh rated ZBM3 battery module. This level of modularity enables the application of Redflow’s ZBRFBs in all 3 stationary energy storage market segments - residential, C&I and utility-scale.

VRB Energy Inc.

VRB Energy Inc. (“VRB Energy“) is a Canada-based company specializing in VRFBs. Ivanhoe Electric, traded under sticker symbol IE on NYSE, is a 90% owner of VRB Energy. VRB Energy’s leading product is the VRB-G3-1000 power module with a rating of 1080 kW DC / 1000 kW AC.

The key specifications of the VRB-ESS include:

• Maximum power: 1080 kW DC; 1000 kW AC

• Storage duration: 4 - 8 hours

• Lifetime: 25 years

• RTE: ≤ 85% (DC); ≤ 75% (AC)

Key competency

• IP: VRB Energy has developed proprietary VRFB components including cell stack and vanadium electrolyte formula and processes such as electrolyte manufacturing, electrolyte balancing and shunt current management.

Author’s take

How do the products stack up against each other? The table below shows that:

• VRB Energy’s VRB-ESS leads the rest with regards to RTE with an excellent DC RTE of 85% and AC RTE of 75%.

• Redflow’s Energy Pod200 is the most modular system which should make it the easiest to configure for small incremental energy requirements.

• ESS claims the least toxic electrolyte composed of iron chloride dissolved in a potassium chloride solution.

• Invinity’s VS3-022 is the most deployed product owing to Invinity’s fleet totaling 75 MWh.

• Largo’s VCHARGE is the largest single unit which makes it suitable for the utility-scale market where a single large unit might be preferred.

The author notes the following key trends in the commercialization of RFB technology:

Vertical integration: traditional vanadium mining and trading companies, such as Largo and Bushveld Minerals, are establishing VRFB manufacturing arms with the hope of capitalizing on the increasing importance of vanadium as a critical mineral. The VRFB businesses of these companies will likely be less impacted by the typical wild fluctuations of vanadium prices.

New business models: RFB companies are looking into innovative business strategies such as electrolyte leasing to reduce the capital expenses (upfront cost) of their RFB ESSs.

Modularity: RFBs were traditionally designed for utility-scale applications given the huge footprints of conventional RFBs. However, companies like Redflow have been expanding into the residential and C&I markets quite successfully.